Heat exchanger for cooling fluids



P. D. VAN VLIET HEAT EXCHANGER FOR COOLING FLUIDS June 22, 1954 FiledFeb. 8, 1952 AT R EYJ.

Patented June 22, 1954 HEAT EXCHANGEB/ FOR COOLING FLUIDS Paul D. VanVliet, Chicago, 111., assignor to The Liquid Carbonic Corporation,Chicago, 111., a

corporation of Delaware Application February 8, 1952, Serial No. 270,690

17 Claims. 1

This invention relates to a heat exchanger for cooling fluids, and moreparticularly to a heat exchanger for cooling liquids such as water andother potable liquids for use in drinking fountains, soda bars, etc.

In the design of water and soda or-carbonated water cooling equipmentfor fountain service, space requirements and material costs must both bekept at a minimum. In addition, draws of water, soda, etc. areintermittent and frequently exceed for short intervals the capacity ofthe cooler and condensing unit serving it. This is especially true onwarm days and during certain hours of the day. Under these conditions,it is still necessary to deliver the liquids at or below a predeterminedtemperature, for example, 40 F. This necessitates a rapidly actingcooling system.

In the past, various types of heat exchangers and cooling systems havebeen employed, but

none of these have proved entirely satisfactory.

For many years a water bath with submerged refrigerant, water and sodacoils was standard, but such equipment was bulky, unsanitary and costlydue to the amount of tubing required. Double and triple tube coolershave been used, but though they operate well at steady flow rates withintheir rated capacity, they fail on intermittent over-loads, deliveringat too high a temperature during such loads. The use of a storage tankafter the water cooling coil has proved unsatisfactory since duringoverload operation, the tank fills with partially cooled water and itmust be drawn out completely before water at the desired temperature isagain available even though the draw rate following such overload iswithin the cooler capacity.

It is, therefore, an object of this invention to provide a heatexchanger or cooler that will cool liquids to a desired temperature veryrapidly, supplying the liquid at the desired temperature during periodsof temporary draw exceeding the capacity of the" cooler. Another objectof this invention is to provide a heat exchanger for cooling two liquidssimultaneously. Still another object is to provide a cooler that will0001 two liquids wherein the flow of the liquids is intermittent and thedemand for one of the liquids at times exceeds the capacity of thecooler. Still another object is to provide a heat exchanger for coolinga liquid subject to temporary draws exceeding the capacity of the coolerhaving a precooler, after cooler and storage tank interposedtherebetween, Yet another object is to provide a cooler for cooling twoliquids in which the flow of the liquids through the heat exchanger isin counter-flow relation with the flow of the refrigerant through theunit. A further object is to provide a small, compact, andself-contained, unitary structure having no moving parts in the heatexchanger and which is economical in construction and operation.Additional objects and advantages of this invention will appear as thespecification proceeds.

The invention is shown in an illustrated embodiment by the accompanyingdrawing in which- Fig. 1 is a side view of a heat exchanger for coolingtwo liquids in which a portion of the coils is broken away; Fig. 2 is anend view of the exchanger shown in Fig. 1; Fig. 3 is a schematic of theheat exchanger shown in Figs. 1 and 2; Fig. 4 is a schematic of a heatexchanger for cooling one liquid in which the direction of flow of theliquid in the aftercooler has been reversed.

Figs. 1, 2 and 3 illustrate a heat exchanger or cooler for cooling twoliquids such as water and a carbonated water or soda useful for fountainservice. The unit consists of a tube shaped to form a helically woundcoil l0 through which a refrigerant or coolant flows and expands throughthe heat exchanger. Each turn of the coil I0 is separated from theadjacent turns to form a small spacing therebetween. The coil isprovided with an inlet-fitting H and an outlet-fitting l2 connecting thecoil Hi to an expansion valve, condenser, and remainder of arefrigerating or cooling unit which is not shown. 'Since refrigeratingunits are old and well-known in the art, it is not believed that adetailed discussion of such is necessary. The material from which thecoil ii! is constructed may be of any metal having a high thermalconductivity such as copper. In the illustration given, the flow of therefrigerant through the coil ll) is from the left to the right.

A helically wound tube forming a water coil i3 is wound parallel to therefrigerant coil as along the outer surface thereof and in thermalcontact with the surface of the coil Ill. The coil I3 is divided intotwo sections or components, a precooler 43a and aftercooler i312. Thedirection of flow of the liquid through the coil [3 is in counterflowrelation to the flow of refrigerant through the coil ID, at least in theprecooler component of the coil [3.

The water coil I 3 is provided with an inletfitting l4 and anoutlet-fitting i5. Water is introduced through the fitting l4 into thecoil It at the right end or precooler component 13a, as seen moreclearly in Fig. 3. When a draw is made, the water in the precooler ifiaflows through the turns, entering the turn it from which it flowsthrough the pipe ll into a storage tank it. The water is drawn from theopposite end of the tank 18 and flows in thelopposite direction, thatis, in the same direction as the refrigerant flow, through theaftercooler component itb'oi the coil l3, or from the left to the rightin Figs. 1 and 3 and through the turn 19 which is connected to the waterout-fitting it. Any suitable metal having a high thermal conductivitysuch as copper may be used to form the coil i3.

In fountain service, water is often subject to temporary overdrawsexceeding the capacity of the heat exchanger. The tank 18, therefore,provides a reserve of chilled water to maintain delivery of water at thedesired temperature during the time interval required to start the re"frigerant flowing through the coil iii. Any suitable material may beused to form the tank 5%. A plug 2! is provided at the withdrawal end atthe bottom of the tank is for draining the liquid therefrom duringcleaning. The tank i8 is separatedirom the inner coil 2t by spacers 22.The spacers 22 are provided at approximately 0 intervals about thesurface of the tank is and extend longitudinally along the tank tomaintain it in spaced-apart relation with the inner coil 2s. The waterout-tube 23 may have an aperture 2 in one wall at a point in the upperportion of the tank to purge air from the system.

The tube forming the helical coil 28 is wound so that each turn isspaced-apart from the ad jacent turn by a distance permitting the coilturns to be positioned along the inner side 01" the refrigerant coil itwithin the spacings provided between each turn of the refrigerant coil.Positioning the carbonated water or soda coil 23 in this manner has beenfound eilective in obtaining the desired cooling since it permitscontact with the refrigerant coil lo along two sides or each turn or thesoda coil 26. The coil is is preferably made of a non-corrosive materialsuch as stainless steel or monel metal and the thermal conductivity ofsuch metals is relatively low. Thus, permitting each turn or the coil2E) to contact two turns of the refrigerant coil It tends to compensatefor the lower ther mal conductivity of these metals.

The coil 25 is provided with an inlet-fitting 125 and an outlet-fitting2t. Soda is not generally subject to overloads or overdraws as is water,and it is not necessary to provide a storage tanlr for the storage ofsoda. It has been found that sufficient cooling is. had when the how ofsoda through the coil is in counter-flow relation with the'flow ofrefrigerant through the coil ill, that is, from the right to the left ofthe exchanger shown in Figs. 1 and 3. All of the turns forming the coilsl3 and 2d are sweated to the coil it to insure a good thermal coupling.The inlet and outlet fittings are securely fastened to a junction plate2'5 to assure proper alignment.

The bulbwells 2S and 29 are made of a metal having a high thermalconductivity such'as copper and form respectively receptacles for thetemperature sensitive portion of the control to start the condensingunit, and for the term perature sensitive portion of the thermal controlon the refrigerant suction line controlling the operation of theexpansion valve in the feed of refrigerant into the'coil l6. Thebulbwell 28,

receiving the bulb for the control which'starts and stops thecondensingunit, is positioned inthermal contact with the first few turns of theprecooler coil l3 and also in thermal contact with the input line 39 ofthe soda coil 20. Either the incoming warm soda or the incoming warmwater will then cause the temperature control tolstart the condensingunit. When liquid is not being drawn from the unit, the chilled waterfrom the tank it will cool the bulbwell and thereby render therefrigerant condensing unit inoperative. The :bulbwell 29 receives thethermal bulb controlling the thermal expansion valve in the refrigerantfeed line, and is positioned in thermal contact with the first few turnsof the precooler 13a.

The ratio of turns in the precooler and aftercooler of the water coil Itshould be of such length (or surface) as to reduce the temperature ofthe incoming water to the desired delivery temperature. It has beenfound that results are good where the ratio of turns in the precooler tothe aftercooler is approximately equal to the product of the inverseratio of the average temperature difference between the refrigerant andwater in the pre to after cooler, times the ratio of the cooling loadsin the pre to after cooler.

For example, if the temperature of the incoming water is F. and it isdesired to reduce the temperature of the liquid feed to the storage tankis to 45 F. through the precooler and to further reduce the temperatureof the liquid through the aftercooler to a so F. delivery temperature,the ratio of the loads or temperature reductions in the pre and aftercoolers is 7 to 1. However, if the temperature of the refrigerantflowing through the coil It is 34 E, the ratio of the difference betweenthe average temperature of the liquid in the precooler and therefrigerant to the difference between the temperature of the liquid inthe aftercooler and the refrigerant is 3 to 1. The ratio of the numberof turns in the 'prec'ooler to the aftercooler. is determinedas the ithe temperature oi the liquid in the after to precooler (l to 3), timesthe ratio of the cooling loads in the pre and after coolers (7 to 1).The product then is /3, or '7 turns in the precooler for every 3 turnsinthe aftercooler.

It has been found that satisfactory results are obtained in reducing thetemperature in accordance with the values above indicated where arefrigerant coil of 23 turns having an inner diameter of approximately5.4 inches, and a water coil with a like number of turns having 7 tiu'nsincluded in the aftercooler' portion are used. Soda is reduced to acorresponding temperature by using a coil having approximately 23continuous turns.

The above temperature reductions were obtained using the coil dimensionsstated where the flow of water was intermittent at a rate of 40 gallonsper hour for 7 seconds, zero flow for 7%; seconds, and then repeated;flow of soda was 15 gallons per hour for 7 /2 seconds, zero for 7seconds, and then repeated; tank capacity was gallon; refrigerant tubesize sufiicient to give a refrigerant gas outlet velocity at full loadof about 2,800 feet per minute; and the condensing unit control set tostart the condensing unit before the. third six ounce'draw. The numberof turns in each coil and the direction of flow of the fluidstherethrough in accordance with the above specific example can best beseen by reference to Fig. 3.

Fig. 4 illustrates a modification of the cooler shown in Figs. 1, 2 and3. In the modified form illustrated, only a single liquid is cooled tothe desired temperature. This unit would have particular utility inwater cooler drinking fountains. The function of the cooler andconstruction is generally the same as the heat exchanger discussedabove. However, the water coil [3 is placed along the inner surface ofthe refrigerant coil It in a position so that each turn of the coil 13is in thermal contact with the refrigerant coil along two surfaces.This, of course, facilitates heat exchange.

The direction of flow of the liquid has been changed from that shown inFig. 3 through the aftercooler section l3b' of the coil. [3, and isdelivered through the aftercooler in a direction of flow counter to theflow of refrigerant through the coil Ill. Changing the direction of flowthrough the aftercooler is not a necessary modification in the watercooler, and the. flow of liquid through the aftercooler may be in thedirection of refrigerant flow as shown in Fig. 3. Likewise, thedirection of flow through the aftercooler of Fig. 3 could be reversed sothat water would be delivered through the aftercooler in a directionopposite or counter to the flow of refrigerant through the coil Ill.

The primary purpose of using counter-flow in the precooler and placingthe precooler at the exit end of the refrigerant coil is to insure ahigh superheat in the outgoing expanded refrigerant whose last pass isin heat exchange relation with the warm incoming water. This also placesthe aftercooler at the inlet end of the refrigerant coil so that in caseof heavy overdraw, the aftercooler gets refrigerant first and insuflicient quantity to lower the precooled water stored in the tank tothe wanted temperature. i

It is to be understood that the ratio of turns in the pre to aftercooler, total number of turns of all of the coils, storage tank size,etc. may be varied to correspond with condenser and refrigerant capacityto yield the particular temperature reductions desired. If desired, thewhole heat exchanger may be tin-dipped after fabrication to increase theheat exchange capacity of the unit.

During operation at or below the rated capacity of the heat exchanger,the storage tank [8 will be at the temperature of the liquid deliveredbythe precooler, or in the specific example, 45 F. at full load and downto about 38 F. at low load. .When water is drawn, the after- 1 coolerwill further cool the water delivered from the tank It to 40 F. at fullload or to a value below 38 F. at low load. If the following draw isabove the capacity of the system, water warmer than will be deliveredfrom the precooler and fill the tank 18. However, the aftercooler willbe operating at a much higher mean temperature difference, refrigerantto water temperature, and the water delivered from the aftercooler willfurther be reduced to a temperature very close to 40 F. Since periods ofheavy or full loads are temporary, the tank water is very generallybelow 40 F.

The positioning of storage tank [8 within refrigerant coils it not onlymakes the water coolin assembly more compact, but also results in asurprising increase in the capacity of the storage tank to prevent widefluctuations in output water temperature with varying rates of dischargeeven though the storage tank is of comparatively small 6 volume. This isapparently due to the fact that the refrigerant coils maintain thetemperature of the air surrounding the storage tank about or slightlyabove the coolest temperature which the Water will reach in the storagetank. Thus, at low rates of flow the storage tank becomes filled withwater at a temperature approachin the minimum temperature which can beproduced by the refrigerant with the established heat transfor capacity,and in intervening periods of nonuse the temperature of the water in thestorage tank does not appreciably increase because it is surrounded bythe refrigerated air. It is, therefore, unnecessary to insulate thestorage tank, which permits the storage tank to be manufac tured ofrelatively thin metal without insulating coverings, etc. A furtherreduction in cost is achieved by this arrangement in that the storagetank can be of relatively small volume while achieving the desiredresult of preventing wide fluctuation in output water temperature. Inconsequence, the storage tank need not even extend for the full lengthof the refrigerant coils, as indicated in the figures of the drawing.When a tank of shorter length than the refrigerant coils is employed, itis preferred to position it adjacent the upper portion of therefrigerant coils, which in the illustration given is the portionsurrounded by the aftercooler l3b.

While in the foregoin specification I have set forth specific structurein considerable detail for the purpose of illustrating an embodiment ofthe invention, it will be understood that such details may be variedwidely by those skilled in the art without departing from the spirit ofmy invention.

I claim:

1. A heat exchanger for reducing the temperature of a fluid, comprisinga tube forming a coil for the flow of a refrigerant therethrough, a sec-0nd tube forming a coil in heat exchange relation with said refrigerantcoil for the flow therethrough of the fluid to be cooled, saidsecondmentioned coil forming a precooler component adjacent thedownstream end of said refrigerant coil and an aftercooler componentadjacent the upstream end of said refrigerant coil, and a tank for thestorage of precooled fluid interposed between said precooler and saidaftercooler for receiving the precooled fluid after the precoolingthereof.

2. A heat exchanger for reducing the temperature of a fluid, comprisinga tube forming a coil for the flow of a refrigerant therethrough andhaving an inlet and an outlet, a second tube forming a coil in heatexchange relation with said refrigerant coilfor the flow therethrough ofthe fluid to be cooled, said second-mentioned coil forming a precoolercomponent adjacent the outlet of said refrigerant coil and anaftercooler component adjacent the inlet of said refrigerant coil, and atank mounted within said coils for the storage of precooled fluid andbeing interposed between said precooler and said aftercooler forreceiving precooled fluid after the precooling thereof.

3. A heat exchanger for reducing the temperature of a fluid, comprisinga tube for the flow of a coolant therethrough shaped to form a coil,

a second tube for the flow of a fluid therethrough Wound in heatexchange relation with said coolant coil and forming a second coil, saidsecond coil forming a precooler component adjacent the downstream end ofsaid coolant. coil and an aftercooler component adjacent the upstreamend 7 of said coolant coil, the direction of flow of the fluid throughsaid precooler component being in counter-flow relation to the directionof the coolant flow throu h said coolant'coil, and a tank for thestorage of precooled fluid interposed between said precooler and saidaftercooler for receiving precooled fluid after the precooling thereof.

4. A heat exchanger for reducing the temperature of a fluid wherein theflow of fluid through said heat exchanger is intermittent, comprising atube for the flow of a refrigerant therethrough shaped to form a coiland having an inlet end and an outlet end, a second tube for the flow ofa fluid therethrough wound in heat exchange relation with saidrefrigerant coil and forming a second coil, said second coil formin aprecooler component at the outlet end of said refrigerant coil and anaftercooler component at the inlet end of said refrigerant coil, and atanl: for the storage of pre-cooled fluid interposed between saidprecooler and said aftercooler mounted within said coils in spaced-apartrelation therewith.

5. A heat exchanger for reducing the temperature of a liquid wherein theflow of liquid through said exchanger is intermittent and at times inexcess of the heat exchanger capacity for short intervals, comprising atube for the flow of a refrigerant therethrough shaped to form asubstantially helical coil having an inlet section and an outlet sectionand the turns of which are in spaced-apart relation, a second tube forthe flow of a liquid therethrough wound to form a second coil havingeach turn thereof in thermal contact with two adjacent turns of saidrefrigerant coil, said second coil forming a precooler component at theoutlet section of said refrigerant coil and an aitercooler component atthe inlet section of said refrigerant coil, the direction of flow of theliquid through said precooler component bea in counter-flow relation tothe direction of the refrigerant flow through said refrigerant coil, anda tank concentrically mounted within said coils spaced-apart therefromfor the storage of precooled liquid, said tank. being interposed betweensaid precooler and said aftercooler.

6. A heat exchanger for water coolers and the like wherein the flow ofliquid through said exchanger is intermittent and at timesexceedexchange relation with said refrigerant coil and forming a secondcoil, said second coil having a precooler component at the outletsection of said refrigerant coil and an aftercooler component at'theinlet section of said refrigerant coil, a third'tube wound to form athird coil in heat exchange relation with said refrigerant coil for theflow therethrough of the second fluid, and a tank interposed betweensaid precooler and aftercooler for the storage of precooled fluidtherein after the precooling thereof.

8. A heat exchanger for reducing the temperature of two fluidscomprising a tube for the flow of a refrigerant therethrough shaped toform a coil and providing an inlet section and outlet section, a secondtube for the flow of one of the fluids therethrough wound in heatexchange relation with said refrigerant coil and forming a second coil,said second coil having a precooler component at the outlet section ofsaid refrigerant coil and an aftercooler component ing the capacity ofsaid exchanger for short intervals, comprising a helically wound tubeforming a coil for the expansion of a refrigerant therein and having aninlet and spaced therefrom an outlet, a second tube wound parallel withsaid refrigerant tube and in thermal con tact therewith and forming asecond helical coil for the flow of a liquid therethrough, said secondcoil forming aprecooler component at the outlet of said refrigerant coiland an aftercooler component at the inlet of said refrigerant coil, thedirection of flow of the liquid through said precooler component beingopposite to the direction ofthe refrigerant flow through saidrefrigerant coil, and a tank interposed in the liquid flow path fromsaid precooler to said aftercooler for the storage of precooled liquid,said tank being mounted within said coils at the inlet section of saidrefrigerant coil.

7. A heat exchanger for reducing the temperature of two fluidscomprising a tube for the flow of a refrigerant therethrough shaped toform a coil and providing an inlet section and an outlet section, asecond tube for the flow of one of the fluids therethrough wound in heatat the inlet section of said refrigerant coil, a third tube wound toform a third coil in heat exchange relation with said refrigerant coilfor the flow therethrough of the second fluid, and a tank interposedbetween said precooler and aftercooler for the storage of preccoledfluid therein after the precooling thereof and being mounted within saidcoils.

9. A heat exchanger for reducing the temperature of two fluids,comprising a tube for the flow of a coolant therethrough shaped to forma coil having inlet and outlet sections, a second tube for the flow ofone of the fluids therethrough wound in heat exchange relation with saidcoolant coil and forming a second coil, said second coil having aprecooler component at the outlet section of said coolant coil'and anaftercooler component at the inlet section of said coolant coil, thedirection of flow of the fiuid through said precooler component being incounter-flow relation to the direction of the coolant fiow through saidcoolant coil, a third tube wound to form a third coil in heat exchangerelation with said coolant coil for the flow of the other fluidtherethrough, the direction of flow through said third tube being in adirection opposite to the flow of coolant through said coolant coil, anda tanlr interposed between said precooler and aftercooler for thestorage of precooled fluid therein after the precooling thereof.

10. A heat exchanger for reducing the temperature of two fluids whereinthe flow of said fluids through said exchanger is intermittent,comprising a tube for the fiow of a refrigerant therethrough shaped toform a substantially helical coil and having inlet and outlet sections,a second tube for the how of a fluid therethrough wound in heat exchangerelation with said refrigerant coil and forming a second coil, saidsecond coil forming a precooler component at the outlet section of saidrefrigerant coil and an aftercooler component at the inlet section ofsaid refrigerant coil, a third tube helically wound and forming a thirdcoil in heat exchange relation with said refrigerant coil for the flowof the second fluid therethrough, the direction of flow through saidthird coil being in a direction opposite to the flow of refrigerantthrough said refrigerant coil, and a tank for the storage of precooledfluid interposed between said precooler and said aftercooler mountedwithin said coils in spaced-apart relation therewith.

11. Aheat exchanger for reducing the temperature of two liquids whereinthe flow of'liquid through said exchanger is intermittent and the flowof one of said liquids is at times in excess of the heat exchangercapacity for short intervals, comprising a tube for the flow of arefrigerant therethrough shaped to form a substantially helical coilhaving the turns thereof in spaced-apart relation, a second tube for theflow therethrough of the liquid subject to temporary over-draws wound toform a second coil having each turn thereof in thermal contact with saidrefrigerant coil, said second coil forming a precooler component at theoutlet section of said refrigerant coil and an aftercooler component atthe inlet section of said refrigerant coil, the direction of flow of theliquid through said precooler component being in counter-flow relationto the direction of the refrigerant flow through said refrigerant coil,a third tube for the flow of the second liquid therethrough wound toform a helical coil having each turn thereof in thermal contact with twoadjacent turns of said refrigerant coil, the direction of flow throughsaid third coil being counter to the flow of refrigerant through saidrefrigerant coil, and a tank concentrically mounted within said coils inspaced-apart relation for the storage of precooled liquid, said tankbeing interposed between said precooler and said aftercooler.

12. A heat exchanger for fountain service adapted to cool two liquidswherein the flow of one of the liquids through said exchanger isintermittent and at times exceeding the capacity of said exchanger forshort intervals, comprising a helically wound tube forming a coil forthe expansion of a refrigerant therein, a second tube wound parallelwith said refrigerant tube along the outer surface thereof and inthermal contact therewith forming a second helical coil for the flowtherethrough of the liquid subject to temporary overdraws, said secondcoil forming a precooler component at the outlet section of saidrefrigerant coil and an aftercooler component at the inlet section ofsaid refrigerant coil, the di-, rection of flow of the liquid throughsaid precooler component being opposite to the direction of therefrigerant flow through said refrigerant coil, a third tube for theflow of the other liquid therethrough wound along the inner surface ofsaid refrigerant coil and forming a third coil in which each turnthereof is in thermal contact with two adjacent turns of saidrefrigerant coil, the flow of the fluid through said third coil being ina direction opposite to the flow of the refrigerant through saidrefrigerant coil, and a tank interposed between said precooler andaftercooler components for the storage of the preoooled liquid, saidtank being concentrically mounted within said coils at the inlet sectionof said refrigerant coil.

13. The structure of claim in which the ratio of the number of turns insaid precooler to the number of turns in said aftercooler issubstantially equal to the product of the inverse ratio of thedifference between the temperature of the refrigerant and the averagetemperature of the liquid in said prcooler to the difference between thetemperature of the refrigerant and the average temperature of the liquidin said aftercooler times the ratio of the temperature change of theliquid in said precooler to the temperature change of the liquid in saidaftercooler.

14. The structure of claim 9 in which the ratio of the number of turnsin said precooler to the number of turns in said aftercooler issubstantially equal to the product of the inverse ratio of thedifference between the temperature of the refrigerant and the averagetemperature of the liquid in said precooler to the difference betweenthe temperature of the refrigerant and the average temperature of theliquid in said aftercooler times the ratio of the temperature change ofthe liquid in said precooler to the temperature change of the liquid insaid aftercooler.

15. A heat exchanger for reducing the temperature of a fluid, comprisinga tube forming a coil for the flow of refrigerant therethrough, a secondtube forming a coil for the flow therethrough of the fluid being cooledand being in heat exchange relation with said refrigerant coil, saidsecond coil forming a precooler component and an aftercooler component,and a tank for the storage of precooled fluid interposed be" tween saidprecooler and said aftercooler for re ceiving and storing the precooledfluid after the precooling thereof.

16. A heat exchanger for reducing the temperature of two fluids,comprising a tube providing a conduit for the flow of a refrigeranttherethrough and being shaped to form a coil, a second tube providing aconduit for the flow of one of the fluids therethrough and being woundto form a second coil in heat exchange relation with saidfirst-mentioned coil, said second-mentioned coil having a precoolercomponent and an aftercooler component, a third tube forming a thirdcoil and being in heat exchange relation with said first mentioned coiland providing a conduit for the flow therethrough of the second fluid tobe cooled, and a tank interposed between said precooler and saidaftercooler and in the fluid flow path therebetween for storing thefluid flowing therein after the precooling thereof.

17. A heat exchanger for reducing the temperature of a liquid,comprising a precooler and an aftercooler each providing a continuouspassage for the flow therethrough of the liquid to be cooled, a storagetank interposed in the flow path between said precooler and saidaftercooler for receiving and storing liquid therein after theprecooling thereof, and a refrigerant expansion coil in heat exchangerelation with said precooler and aftercooler whereby the refrigerantexpanding through said coil reduces the temperature of the liquidflowing through said precooler and said aftercooler, said refrigerantcoil being spaced from said storage tank.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,802,396 Taylor Apr. 28, 1931 1,911,042 Steenstrup May 23,1933 1,972,844 Killen Sept. 4, 1934 2,339,229 Wyllie Jan. 11, 19442,531,315 Wyllie Nov, 21, 1950

